On 24 January 2016 at 21:17, Maciej W. Rozycki <[email protected]> wrote: > On Sun, 17 Jan 2016, Rafał Miłecki wrote: > >> KSEG0ADDR was translating 0x1c000000 into 0x9c000000. With >> ioremap_cachable we use MIPS's __ioremap (and remap_area_pages). This >> results in different address (e.g. 0xc0080000) but it still should be >> cached as expected and it was successfully tested with BCM47186B0. > > This is due to this piece: > > /* > * Map uncached objects in the low 512mb of address space using KSEG1, > * otherwise map using page tables. > */ > if (IS_LOW512(phys_addr) && IS_LOW512(last_addr) && > flags == _CACHE_UNCACHED) > return (void __iomem *) CKSEG1ADDR(phys_addr); > > special-casing uncached mapping only (replicated in 2 places). I think > there will really be no harm from returning a KSEG0 mapping for calls > requesting a caching mode equal to `_page_cachable_default', which -- > depending on the cache architecture -- will have been either hardwired or > prearranged via Config.K0. I think there's really no need to put pressure > on the TLB, which may be small, in cases where a fixed mapping will do.
No, it isn't hitting condition you pointed. We call ioremap_cachable which uses _page_cachable_default as a flag. This flag (_page_cachable_default) isn't equal to the _CACHE_UNCACHED. Moreover code you pointed uses CKSEG1ADDR which would result in setting bit KSEG1 (0xa0000000). As I pointed in the commit message address it ORed with KSEG2 (0xc0000000). So what really happens is what my commit message says: ioremap_cachable -> __ioremap -> remap_area_pages
